Using a panel of patient cell lines with chromosomal breakpoints, we constructed a physical map for the short arm of human chromosome 11. We focused on 11p15, a chromosome band harboring at least 25 known genes and associated with the Beckwith-Wiedemann syndrome, several childhood tumors, and genomic imprinting. This underlines the need for a physical map for this region. We divided the short arm of chromosome 11 into 18 breakpoint regions, and a large series of new and previously described genes and markers was mapped within these intervals using fluorescence in situ hybridization. Cosmid fingerprint analysis showed that 19 of these markers were included in cosmid contigs. A detailed 10-Mb pulsed-field physical map of the region 11p15.3-pter was constructed. These three different approaches enabled the high-resolution mapping of 210 markers, including 22 known genes.